Metabolism and Degradation of Glyphosate in Soil and Water

Abstract

Complete and rapid degradation of glyphosate [N-phosphonomethylglycine (1)] occurs in soil and/or water microbiologically and not by chemical action. Using soil/water shake flasks, up to 50% of each carbon of 1-14C was evolved as 14CO2 in 28 days. In two of the three soils examined, 1 was 90% dissipated in less than 12 weeks. Aminomethylphosphonic acid (2), the only significant soil metabolite of 1, also undergoes rapid degradation in soil. Short-term shake flask metabolism experiments with both 13C and 14C-labeled 1 were carried out in order to permit facile, unequivocal spectral identification of 1 and its transient metabolite aminomethylphosphonic acid (2). Comparison of the metabolic samples to both reference standards and the spiked controls by means of 1H, 31P, and 13C NMR, mass spectral analysis, ion-exchange chromatography, and thin-layer chromatography has unequivocally characterized both bound and unbound 1 and 2 in soil. The parent herbicide 1 has also been shown to be stable to sunlight, nonleachable in soil, to have a low propensity for runoff, and to have a minimal effect on microflora. © 1977, American Chemical Society. All rights reserved.